The ischial tuberosity (or tuberosity of the ischium, tuber ischiadicum), also known informally as the sit bones, or as a pair the sitting bones is a large swelling posteriorly on the superior ramus of the ischium. It marks the lateral boundary of the pelvic outlet.
Capsule of hip-joint (distended). Posterior aspect. (Ischial tuberosity visible at bottom left.)
The superficial branches of the internal pudendal artery. (Ischial tuberosity visible at center left.)
|Latin||Tuber ischiadicum, tuberositas ischiadica|
|Anatomical terms of bone|
When sitting, the weight is frequently placed upon the ischial tuberosity. The gluteus maximus provides cover in the upright posture, but leaves it free in the seated position. The distance between a cyclist's ischial tuberosities is one of the factors in the choice of a bicycle saddle.
The tuberosity is divided into two portions: a lower, rough, somewhat triangular part, and an upper, smooth, quadrilateral portion.
- The lower portion is subdivided by a prominent longitudinal ridge, passing from base to apex, into two parts:
- The upper portion is subdivided into two areas by an oblique ridge, which runs downward and outward:
The Obturator externus.
- Sills, Franklyn (2004). Craniosacral Biodynamics: The Primal Midline and the Organization of the Body (revised, illustrated ed.). Berkeley, CA: North Atlantic Books. p. 99. ISBN 1-55643-390-5.
- Goossens (2005), pp 895–982
- Platzer (2004), p 236
- Anatomy photo:41:st-0204 at the SUNY Downstate Medical Center - "The Female Perineum: Bones"
- Anatomy photo:17:os-0114 at the SUNY Downstate Medical Center - "Major Joints of the Lower Extremity: Hip bone (lateral view)"
- pelvis at The Anatomy Lesson by Wesley Norman (Georgetown University) (pelvisposterior, pelvislateral, pelvisinside)